Wearable lignin-based hydrogel electronics: A mini-review

1. Introduction 45 2. Feasible design routes of lignin-based hydrogel electronics 46 2.1. Lignin and its derivatives as conductive fillers for hydrogel 46 2.2. Lignin and its derivatives as adhesive agents for hydrogel 46 2.3. Lignin and its derivatives as strength modifier of hydrogel 48 2.4. Lignin and its derivatives as functional fillers of hydrogel 48 2.5. Lignin and its derivatives as catalysts of hydrogel fabrication 48 In recent years, various biomacromolecule-based hydrogels have been extensively and deeply studied in the field of wearable electronics. However, the application of lignin-based hydrogels in flexible devices is still in its infancy. This is mainly due to the significant differences in physical and chemical properties of industrially extracted lignin. In order to seek the universal applicability of diversified lignin in the preparation of hydrogel electronics, we mainly paid attention to the natural physical and chemical properties of lignin to discuss feasible solutions for functional gel design. These properties include chemical reactivity, UV shielding, antibacterial, biodegradability, anti-oxidation, etc. Finally, in view of lignin's unique properties and the demand for high-quality flexible electronics, some insights are proposed regarding the future research and development directions of lignin-based hydrogel electronics. (c) 2021 Elsevier B.V. All rights reserved.